Add all dart:html tests from the sdk to test/codegen.

test/codegen/lib/html/htmlelement_test.dart

+library ElementTest;
+import 'package:unittest/unittest.dart';
+import 'package:unittest/html_config.dart';
+import 'dart:html';
+import 'utils.dart';
+
+main() {
+  useHtmlConfiguration();
+  test('InnerHTML', () {
+    Element element = new Element.tag('div');
+    element.id = 'test';
+    element.innerHtml = 'Hello World';
+    document.body.append(element);
+
+    element = document.query('#test');
+    expect(element.innerHtml, 'Hello World');
+    element.remove();
+  });
+  test('HTMLTable', () {
+    Element table = new Element.tag('table');
+
+    TableRowElement row = new Element.tag('tr');
+    table.append(row);
+
+    row.append(new Element.tag('td'));
+    row.append(new Element.tag('td'));
+
+    expect(row.cells.length, 2);
+
+    TableRowElement headerRow = table.rows[0];
+    expect(headerRow.cells.length, 2);
+  });
+  test('dataset', () {
+    Element div = new Element.tag('div');
+
+    expect(div.dataset.isEmpty, isTrue);
+    expect(div.dataset['foo'], isNull);
+    expect(div.dataset.isEmpty, isTrue);
+
+    div.dataset['foo'] = 'foo-value';
+    expect(div.dataset['foo'], 'foo-value');
+    expect(div.dataset.isEmpty, isFalse);
+
+    expect(div.dataset.containsValue('foo-value'), isTrue);
+    expect(div.dataset.containsValue('bar-value'), isFalse);
+    expect(div.dataset.containsKey('foo'), isTrue);
+    expect(div.dataset.containsKey('bar'), isFalse);
+
+    bool hasBeenInvoked;
+    String f() {
+      hasBeenInvoked = true;
+      return 'bar-value';
+    }
+
+    hasBeenInvoked = false;
+    expect(div.dataset.putIfAbsent('bar', f), 'bar-value');
+    expect(hasBeenInvoked, isTrue);
+
+    hasBeenInvoked = false;
+    expect(div.dataset.putIfAbsent('bar', f), 'bar-value');
+    expect(hasBeenInvoked, isFalse);
+
+    final keys = <String> [];
+    final values = <String> [];
+    div.dataset.forEach((String key, String value) {
+        keys.add(key);
+        values.add(value);
+    });
+    expect(keys, unorderedEquals(['foo', 'bar']));
+    expect(values, unorderedEquals(['foo-value', 'bar-value']));
+
+    expect(new List<String>.from(div.dataset.keys),
+        unorderedEquals(['foo', 'bar']));
+    expect(new List<String>.from(div.dataset.values),
+        unorderedEquals(['foo-value', 'bar-value']));
+
+    expect(div.dataset.length, 2);
+    expect(div.dataset.isEmpty, isFalse);
+
+    expect(div.dataset.remove('qux'), isNull);
+    expect(div.dataset.length, 2);
+    expect(div.dataset.isEmpty, isFalse);
+
+    expect(div.dataset.remove('foo'), 'foo-value');
+    expect(div.dataset.length, 1);
+    expect(div.dataset.isEmpty, isFalse);
+
+    div.dataset.clear();
+    expect(div.dataset.length, 0);
+    expect(div.dataset.isEmpty, isTrue);
+
+    Element otherDiv = new Element.html(
+        '<div id="dataDiv" data-my-message="Hello World"></div>',
+        treeSanitizer: new NullTreeSanitizer());
+    expect(otherDiv.dataset.containsKey('myMessage'), isTrue);
+
+    Element anotherDiv = new Element.html(
+        '<div id="dataDiv" data-eggs="bacon"></div>',
+        treeSanitizer: new NullTreeSanitizer());
+    expect(anotherDiv.dataset.containsKey('eggs'), isTrue);
+  });
+}